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rtt.go
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rtt.go
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package consul
import (
"fmt"
"sort"
"github.com/hashicorp/consul/agent/structs"
"github.com/hashicorp/consul/lib"
)
// nodeSorter takes a list of nodes and a parallel vector of distances and
// implements sort.Interface, keeping both structures coherent and sorting by
// distance.
type nodeSorter struct {
Nodes structs.Nodes
Vec []float64
}
// newNodeSorter returns a new sorter for the given source coordinate and set of
// nodes.
func (s *Server) newNodeSorter(cs lib.CoordinateSet, nodes structs.Nodes) (sort.Interface, error) {
state := s.fsm.State()
vec := make([]float64, len(nodes))
for i, node := range nodes {
_, other, err := state.Coordinate(node.Node, nil)
if err != nil {
return nil, err
}
c1, c2 := cs.Intersect(other)
vec[i] = lib.ComputeDistance(c1, c2)
}
return &nodeSorter{nodes, vec}, nil
}
// See sort.Interface.
func (n *nodeSorter) Len() int {
return len(n.Nodes)
}
// See sort.Interface.
func (n *nodeSorter) Swap(i, j int) {
n.Nodes[i], n.Nodes[j] = n.Nodes[j], n.Nodes[i]
n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
}
// See sort.Interface.
func (n *nodeSorter) Less(i, j int) bool {
return n.Vec[i] < n.Vec[j]
}
// serviceNodeSorter takes a list of service nodes and a parallel vector of
// distances and implements sort.Interface, keeping both structures coherent and
// sorting by distance.
type serviceNodeSorter struct {
Nodes structs.ServiceNodes
Vec []float64
}
// newServiceNodeSorter returns a new sorter for the given source coordinate and
// set of service nodes.
func (s *Server) newServiceNodeSorter(cs lib.CoordinateSet, nodes structs.ServiceNodes) (sort.Interface, error) {
state := s.fsm.State()
vec := make([]float64, len(nodes))
for i, node := range nodes {
_, other, err := state.Coordinate(node.Node, nil)
if err != nil {
return nil, err
}
c1, c2 := cs.Intersect(other)
vec[i] = lib.ComputeDistance(c1, c2)
}
return &serviceNodeSorter{nodes, vec}, nil
}
// See sort.Interface.
func (n *serviceNodeSorter) Len() int {
return len(n.Nodes)
}
// See sort.Interface.
func (n *serviceNodeSorter) Swap(i, j int) {
n.Nodes[i], n.Nodes[j] = n.Nodes[j], n.Nodes[i]
n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
}
// See sort.Interface.
func (n *serviceNodeSorter) Less(i, j int) bool {
return n.Vec[i] < n.Vec[j]
}
// serviceNodeSorter takes a list of health checks and a parallel vector of
// distances and implements sort.Interface, keeping both structures coherent and
// sorting by distance.
type healthCheckSorter struct {
Checks structs.HealthChecks
Vec []float64
}
// newHealthCheckSorter returns a new sorter for the given source coordinate and
// set of health checks with nodes.
func (s *Server) newHealthCheckSorter(cs lib.CoordinateSet, checks structs.HealthChecks) (sort.Interface, error) {
state := s.fsm.State()
vec := make([]float64, len(checks))
for i, check := range checks {
_, other, err := state.Coordinate(check.Node, nil)
if err != nil {
return nil, err
}
c1, c2 := cs.Intersect(other)
vec[i] = lib.ComputeDistance(c1, c2)
}
return &healthCheckSorter{checks, vec}, nil
}
// See sort.Interface.
func (n *healthCheckSorter) Len() int {
return len(n.Checks)
}
// See sort.Interface.
func (n *healthCheckSorter) Swap(i, j int) {
n.Checks[i], n.Checks[j] = n.Checks[j], n.Checks[i]
n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
}
// See sort.Interface.
func (n *healthCheckSorter) Less(i, j int) bool {
return n.Vec[i] < n.Vec[j]
}
// checkServiceNodeSorter takes a list of service nodes and a parallel vector of
// distances and implements sort.Interface, keeping both structures coherent and
// sorting by distance.
type checkServiceNodeSorter struct {
Nodes structs.CheckServiceNodes
Vec []float64
}
// newCheckServiceNodeSorter returns a new sorter for the given source coordinate
// and set of nodes with health checks.
func (s *Server) newCheckServiceNodeSorter(cs lib.CoordinateSet, nodes structs.CheckServiceNodes) (sort.Interface, error) {
state := s.fsm.State()
vec := make([]float64, len(nodes))
for i, node := range nodes {
_, other, err := state.Coordinate(node.Node.Node, nil)
if err != nil {
return nil, err
}
c1, c2 := cs.Intersect(other)
vec[i] = lib.ComputeDistance(c1, c2)
}
return &checkServiceNodeSorter{nodes, vec}, nil
}
// See sort.Interface.
func (n *checkServiceNodeSorter) Len() int {
return len(n.Nodes)
}
// See sort.Interface.
func (n *checkServiceNodeSorter) Swap(i, j int) {
n.Nodes[i], n.Nodes[j] = n.Nodes[j], n.Nodes[i]
n.Vec[i], n.Vec[j] = n.Vec[j], n.Vec[i]
}
// See sort.Interface.
func (n *checkServiceNodeSorter) Less(i, j int) bool {
return n.Vec[i] < n.Vec[j]
}
// newSorterByDistanceFrom returns a sorter for the given type.
func (s *Server) newSorterByDistanceFrom(cs lib.CoordinateSet, subj interface{}) (sort.Interface, error) {
switch v := subj.(type) {
case structs.Nodes:
return s.newNodeSorter(cs, v)
case structs.ServiceNodes:
return s.newServiceNodeSorter(cs, v)
case structs.HealthChecks:
return s.newHealthCheckSorter(cs, v)
case structs.CheckServiceNodes:
return s.newCheckServiceNodeSorter(cs, v)
default:
panic(fmt.Errorf("Unhandled type passed to newSorterByDistanceFrom: %#v", subj))
}
}
// sortNodesByDistanceFrom is used to sort results from our service catalog based
// on the round trip time from the given source node. Nodes with missing coordinates
// will get stable sorted at the end of the list.
//
// If coordinates are disabled this will be a no-op.
func (s *Server) sortNodesByDistanceFrom(source structs.QuerySource, subj interface{}) error {
// We can't sort if there's no source node.
if source.Node == "" {
return nil
}
// We can't compare coordinates across DCs.
if source.Datacenter != s.config.Datacenter {
return nil
}
// There won't always be coordinates for the source node. If there are
// none then we can bail out because there's no meaning for the sort.
state := s.fsm.State()
_, cs, err := state.Coordinate(source.Node, nil)
if err != nil {
return err
}
if len(cs) == 0 {
return nil
}
// Do the sort!
sorter, err := s.newSorterByDistanceFrom(cs, subj)
if err != nil {
return err
}
sort.Stable(sorter)
return nil
}